Discussion

Some interesting activity has been occurring in recent days at both polar regions in terms of cold weather and sea ice areal extent. To begin with, this is turning out to be one of the coldest summers ever recorded in and around the North Pole according to the Danish Meteorological Institute (DMI). Furthermore, on the other side of the globe, the southern hemisphere sea ice areal extent is once again right near a record high for the date and it has a chance to end up near all-time record highs for the region over the next several weeks.

The DMI, Center for Ocean and Ice, estimates the daily mean temperature of the Arctic region north of 80 degrees using analysis data (00 and 12Z) from the European computer forecast model for all model grid points inside that area. The DMI produces a chart plotting this daily mean temperature as a function of the day of the year against the average of the daily mean temperature for the period from 1958 to 2002. In fact, the daily mean temperatures in this Arctic region has remained below the climatological normal for more than 4 months now and it has dropped below freezing far earlier than normal for this area. Normally, the drop below freezing does not occur until the middle part of September. The sea ice areal extent in the northern hemisphere continues to run at well below normal levels, but with the colder-than-normal weather north of 80 degrees this summer, there has been a noticeable uptick in northern hemisphere sea ice areal extent in recent weeks relative to several recent years. The overall northern hemisphere sea ice areal extent has generally been below normal since the mid-1990s at which time the northern Atlantic Ocean developed warmer-than-normal sea surface temperatures which is tracked by meteorologists through an index called the Atlantic Multidecadal Oscillation (AMO). The AMO index switched to a warm or positive phase in the middle 1990s reflective of an oceanic cycle of warmer-than-normal sea surface temperatures. Meanwhile, the southern hemisphere which is moving through their winter season continues to impress with its sea ice areal extent. Indeed, the most recent measurements suggest it is near a record high for the date and may come close to all-time record highs in areal extent over the next several weeks using records that go back to the beginning of the satellite era (1979).